Occasional mmc0 timeout on 2.6.25 master kernels

[Denver Gingerich]

On Fri, May 2, 2008 at 12:12 PM, C. Scott Ananian <cscott at laptop.org> wrote:
>
> On Thu, May 1, 2008 at 10:52 PM, Denver Gingerich <denver at ossguy.com> wrote:
>  > When booting 2.6.25 master kernels (specifically seen on 20080501.2
>  >  and 20080501.3) from an SD card, the following error occurs every 5th
>  >  boot or so:
>  >
>  >  [ 3.512185] Waiting 2sec before mounting root device...
>  >  [ 5.574603] VFS: Cannot open root device "mmcblk0p1" or unknown-block(0,0)
>  >  [ 5.577210] Please append a correct "root=" boot option; here are the
>  >  available partitions:
>  >  ...
>  >  [ 5.747213] Kernel panic - not syncing: VFS: Unable to mount root fs
>  >  on unknown-block(0,0)
>  >  [13.597220] mmc0: Timeout waiting for hardware interrupt.
>  >
>  >  I have never encountered this error using 2.6.22-20071121.7 with over 50 boots.
>
>  Does increasing rootdelay help?  ie, is the problem that setting up SD
>  is now taking (say) 1.5-2.5 seconds instead of 1-2 seconds, and so
>  sometimes the SD card is not present after the 2 second rootdelay?

I can give it a shot, but I don't think it will help.
2.6.22-20071121.7 always ran fine with rootdelay=1 and when I first
got the mounting problem on 2.6.25 I increased it to rootdelay=2.  But
the mounting problems continued after making that change.  The type of
error (mmc0 timeout) suggests that there are communication problems
with the SD controller that would prevent the kernel from finding the
partition table, even after waiting 10 seconds (the apparent length of
the timeout given the timestamps).

Denver